#' Loss distribution elbow plot.
#'
#' Boxplots of the loss from \code{min.dim} to \code{max.dim} \code{k} values.
#'
#' @param x Object of class \code{"cve"} (result of [\code{\link{cve}}]).
#' @param ... Pass through parameters to [\code{\link{plot}}] and
#'      [\code{\link{lines}}]
#'
#' @seealso see \code{\link{par}} for graphical parameters to pass through
#'      as well as \code{\link{plot}}, the standard plot utility.
#' @method plot cve
#' @importFrom graphics plot lines points boxplot
#' @export
plot.cve <- function(x, ...) {
    L <- c()
    k <- c()
    for (dr.k in x$res) {
        if (class(dr.k) == 'cve.k') {
            k <- c(k, as.character(dr.k$k))
            L <- c(L, dr.k$L)
        }
    }
    L <- matrix(L, ncol = length(k)) / var(x$Y)
    boxplot(L, main = "elbow plot",
            xlab = "SDR dimension",
            ylab = "Sample loss distribution",
            names = k)
}